Process for the manufacture of photographic films and of carriers for the same



Patented Apr. 16, 1935 UNITED STATES PROCESS FOR THE MANUFACTURE OF PHO-TOGRAPHIC FILMS AND OF CARRIERS FOB THE SAME Max Ranker,Duren/Rheinland, Germany No Drawing. Application August 20, 1931, SerialNo. 558,419. In Germany August 24, 1929 10 Claims.

The object of the application is a process for the manufacture of asubstitute for the expensive celluloid films hitherto generally used inphotography.

There has already been suggested for photographic or kinematographicfilms a substitute, obtained through making transparent my usual paperby dipping it into resin or oil solutions, and then coating it withphotographic emulsion. Substitute films manufactured in this way aresufiiciently transparent and show no granulation. They have thedisadvantage, however, that in the water-or even more inalkali-developing baths used in photography they soften very much and toa great extent lose their transparency. Furthermore, they turn so yellowin the course of time that they can no longer be used in the manufactureof reproductions. Another drawback of the oil tracing-paper films isthat the oil preparation has an unfortunate effect upon the photographicemulsions.

The applicant has found that these disadvantages may be completelyremoved and that films may be obtained capable of replacing in the mostvaried ways the expensive celluloid films, both on account of theirtransparency and of their durability. Such films may be obtained byusing as a foundation a transparent or translucent parchment-substitutepaper, especially Pergamyn paper, that is to say a grease-ground paperor a sharply satinized parchment-substitute paper, and by covering it onone or both sides with a coating of varnish, upon which is laid aphotographically sensitive gelatine emulsion. For the preparation of theparchment-substitute paper used as a-foundation, cellulose varnishes arepeculiarly suitable, e. g. those containing cellulose ester, celluloseether, or a mixture of both in so- I lution. Films manufactured in thisway are.

highly transparent, and possess likewise all the necessary durability.

In order to obtain a particularly firm fixing of the coating ofcellulose varnish to the foundation, and to prevent a loosening of thesame, the foundation may then preferably be prepared with anintermediary coating, for preference with a suitable solution of resin.This coating will on the one side cling firmly to the grease proofpaper, and will on the other side dissolve to a certain extent into thecellulose-varnish solution which is afterwards laid upon it.

For this purpose the cellulose-varnish solution may with advantage be sochosen that it may to some extent combine with the intermediary resincoating, without completely loosening the latter.

This moderate action of the cellulose-varnish coating on theintermediary resin coating is obtained by dissolving the cellulose esterin a dissolving solution which does not aifect the resin, but whichcontains small quantities, e. g. perhaps 10 to 20% of a good resindissolver.

It has been shown in a surprising manner that not only the durabilityand imperviousness to 10 water of the grease proof paper serving as afoundation, are increased by the above-described process, but also thatthe transparency of the carrier is improved by the use of anintermediary resin coating under the cellulose-varnish coating. 15 Theimprovement in transparency caused by the preparation of the greaseproof paper, e. g. on a coating-machine of known construction, and thenby the application of the intermediary resin layer, and even more so bythe application of the 20 covering cellulose-varnish coat, is striking.

Example of manufacture Transparent satined grease proof paper pro- 25'duced e. g. by a long grinding with blunt knives under squeezing of thethreads, is prepared by coating or spraying with or by dipping into a 10to 20% solution of shellac in spirit. The superfluous liquid is thenmostly scraped oil, and the paper 30 dried over radiators. To this resinlayer is then applied a solution of nitro-cellulose in vinegarether, towhich is added a quantity of spirit equal to between 10 and 20% of thetotal weight. This small quantity of spirit causes a corrosion of the 35resin layer, resulting in a very firm clinging of the cellulose-varnishlayer to the resin layer.

After the drying process a light-sensitive gelatine emulsion is appliedto the cellulose-varnish layer. In order to assure a firm clinging ofthis 40 gelatine emulsion to the paper carrier coated withcellulose-varnish, a thin intermediary coating may preferably beintroduced between the layer of varnish and the light-sensitive gelatinelayer, as already suggested by the applicant. This may e. g. becontrived by the application of a gelatine solution, produced bydissolving gelatine in volatile organic dissolvers e. g. acetic acid,formic acid, alcohols, ketones etc., or in a mixture of these.

It is advantageous to use such dissolvers so as to a small extentdissolve both the gelatine and the varnishes used, e. g. cellulose-esteror -ether.

The intermediary coating is dried hot; then the gelatine emulsion isapplied to the coated side or sides, and at once clings perfectly.

To prevent the rolling or twisting of the emulsionised papers allmeasures proper to the technique of photographic emulsion may be used.

In place of the shellac forming the intermediary building layer betweenthe paper and the cellulose-varnish, other resins or mixtures of resinsmay be used. Care must then be taken that these resins do not dissolvecompletely into the dissolver or dissolving-mixture used for theapplication of the cellulose coating.

An alteration in the carrying-out of the process, which, however, doesnot generally give such good results, consists in the addition at thecommencement of resins or in given cases, of softening means, in orderto improve the strength of the hold upon the paper foundation.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, 1 declare thatwhat! claim is:-

1. A process for the manufacture of photographic films, consisting inthe application to Pergamyn paper of a layer of varnish, and further inthe application to this layer of varnish of a photographicallylight-sensitive layer.

2. A process for the manufacture of photographic films, consisting inthe application to Pergamyn paper of a layer of varnish, and further inthe application to this layer of varnish of a photographic gelatinaemulsion.

3. A process for the manufacture of photographic films, consisting inthe coating of Pergamyn paper on both sides with a layer of varnish, towhich layer is applied a photographic gelatine emulsion.

4. A process for the manufacture of photographic films, consisting inthe preparation of Pergamyn paper with a resin coating, covered with alayer of varnish, to which layer a photographic light-sensitive coatingis applied.

5. 'A process for the manufacture of photographic films, consisting inthe application to sharply satinized parchment-substitute paper of alayer of varnish, to the varnish of a layer of gelatine, and to thegelatine layer of a photographic, light-sensitive layer. a

6. A process for the manufacture of photographic films. in theapplication to sharply satinised parchment-substitute paper ofacoatingofvarnishwhichthenreeelvelacoating of geiatine and lastly aphotographic gelatine emulsion.

7. A process for the manufacture of photographic iilms, consisting inthe covering of sharply satinized parchment-substitute paper with aresin layer, and with a layer of varnish. to which latter is applied acoating of pure gelatine, and finally to the gelatine a photographicgelatine emulsion.

8. A process for the manufacture ofphotographicfilmsconsistinginutilizingasabase Pergamyn paper, apply lthereto a coating of varnish, with an intermediate layer of a characterto adhere to the paper and unite with the varnish, and a light-sensitiveemulsion layer applied to the varnish, the intermediate layer beingwithout deleterious eifect on the normal transparency of the body andsolubly intermingling with the varnish.

9. A process for the manufacture of photographic films consisting inproviding a body of Pergamyn paper, applying a coating of varnishthereto, an intermediate layer'for uniting the varnish and paper, saidlayer having an adhesive eilect on the paper without detracting from thetransparency thereof, the varnish containing a limited proportion of asolvent for the intermediate laver, and a light-sensitive emulsionapplied on the surface of the varnish.

10. A process for the manufacture of photographic fllms consisting inproviding a body of sharply satinized parchment-substitute paper ofnatural transparency, applying a layer of cellulose varnish solutionthereto, with an intermediate binder adhering to the paper and partlysolvent by the cellulose varnish solution, the binder being of acharacter to avoid detracting from the inherent transparency of thepaper, and finally applying a light-sensitive gelatin emulsion to thecellulose varnish through the medium of an intermediary layer of anature to have a limited solvent eflect on the varnish and gelatin 6emulsion.

MAX RENKER.

